FI96110B - Process and device for bending and hardening glass sheets - Google Patents

Abstract

The invention relates to a process and a device for bending and hardening glass sheets. The device comprises a roller conveyor which can be bent into a bow and upper and lower hardening mantels 7, 5 having hardening openings 8, 6. The separate rollers 4 of the conveyor are formed from two or more parts 4a, 4b and are bendable such that the central regions of the rollers 4 can be linked to a level below their ends. At the same time, the pressure rollers 11 which are located on the upper sides are pressed downwards by compressed air cylinders 17. The pressure rollers 11 can, zones by zone, be imparted a desired compressive force for the purpose of producing the desired double bending. <IMAGE>

Description

96110

Method and apparatus for bending and cutting glass sheets. - Förfarande och anordning för böjning och härdning av glasskivor.

The invention relates to a method for bending and tempering glass sheets of the type defined in the preamble of appended claim 1.

The invention also relates to a bending and tempering section for glass sheets comprising a roll conveyor, the mutual height position of the rollers being adjustable to curve the conveyor to a curve corresponding to the desired degree of bending. , having lower surfaces provided with tempering openings, the tempering housings being movable to cause said upper and lower surfaces to follow the curvature of the conveyor. Such a device is known from the applicant's patent publications US-4,881,962 and US-5,057,137. This device has proven to be very useful in the production of bent and tempered building glass.

In this known device, the bending of the glass sheet is based on gravitational bending in a bending and tempering section outside the heating furnace. For this reason, the glass sometimes has to be overheated to the required tempering temperature because the temperature of the glass drops before the glass is completely bent to its desired shape and the tempering of the glass can be initiated.

The cooling of the glass is typically in the order of 10 ° C to 25 ° C, depending on the type of glass and the conditions.

For this so-called. overheating is characterized by an increase in optical defects in the glass and is more easily detected in the final product. 2 Q / C

-7 - * I

Annex.

In addition, this known method and device has the limitation that the glass sheet can be bent with respect to only one axis of curvature.

The object of the invention is to improve the above-mentioned known method and device so that the glass can be bent to achieve double curvature and, in addition, said harmful overheating can be omitted from the process, whereby the temperature of the glass leaving the furnace decreases and the glass optics improve.

This object is achieved by the invention on the basis of the features set out in the appended claim 1 for the method and on the basis of the features set out in the appended claim 5 for the device. Preferred embodiments of the invention are set out in the dependent claims.

When adjustable pressure rollers are added above the glass, gravity bending is converted to mechanical compression bending. In addition, when the glass is supported by rollers of a curved roller conveyor having a central region below the ends, bending is achieved around two mutually perpendicular axes, and in addition, the accuracy of the bending shape of the glass sheet is improved because the bending can be adjusted and forced to the desired shape.

Bending of glass in a combined bending and tempering section with an upper and lower roller system has previously been proposed in U.S. Pat. No. 4,822,398. However, the bending takes place exclusively around the direction of bending of the glass sheet. · '· Double curvature is not obtained, in addition to which smaller radii of curvature cause optical problems due to the fact that during bending the respective rollers on both surfaces of the glass move laterally with respect to the glass, i.e. they slide longitudinally in the transverse direction.

* In this case, it is difficult to meet the requirement of good optical quality.

In the present invention, the bending with a smaller radius of curvature can be selected about an axis transverse to the direction of travel. The flexible suspension method of the press rollers and the adjustable pressing force during bending make it possible to apply the invention to benders in which bending takes place about both a transverse and a directional axis.

In the following, one embodiment of the invention will be illustrated with reference to the accompanying drawings, in which Figure 1 shows a side view of a part of a bending and hardening section; Fig. 2A schematically shows the transition of the glass sheet from the furnace to the bending and tempering section, and Fig. 2B schematically shows the position of the rollers and rollers when the glass sheet has moved to the bending and tempering section; Fig. 3 is a side schematic view of the bending and tempering section during bending; . Fig. 4 shows a top view of the arrangement of the press rollers; Fig. 5 shows a glass sheet in the bending and tempering compartment between the press rollers and the roller conveyor before bending; Fig. 6 shows the same as Fig. 5, but during or after bending 4; and Figure 7 is a perspective view of a bi-directionally bent glass sheet and the location of the press rollers and the bent rollers of the curved conveyor.

4,96110

The furnace 1 is followed by a bending and tempering section 2 with a conveyor 3 formed by rollers 4. Below the glass sheet supported by the rollers 4 are tempering housings 5 and above tempering housings 7. The upper surfaces 9 of tempering housings 5 have nozzle openings 6 and tempering housings 7 have nozzle openings 8 and 7. the nozzles contained therein are not shown and their structure and shape may vary in many ways.

As further described in U.S. Pat. No. 4,881,962 and U.S. Pat. No. 5,057,137, the conveyor 3 can be curved to a curvature corresponding to the desired degree of bending of the glass. Any mechanism by which the rollers 4 are caused to move vertically relative to each other can be considered. The nozzle housings 5 and 7 are arranged to be moved in a corresponding manner so that the curvature of the upper and lower housing rows corresponds to the curvature of the conveyor 3. In this case, the housing surfaces 9 and 10 remain substantially at the same distance from the surface of the glass, whereby the glasses can be tempered efficiently and evenly, regardless of their degree of bending.

The greater curvature of the double curvature (with a smaller radius of curvature) is caused by curving the conveyor and the lower curvature (with a larger radius of curvature) is caused by deflection or curvature of the rollers 4, 4 ', as shown in Figures 5-7. Achieving such a double curvature requires • · a specially adjustable mechanical pressing from above.

Attached to the upper hardening housings 7 are a number of pressure rollers 11, each of which is separately arranged by a pneumatic cylinder 17 to be moved between an upper rest position and a lower working position. Axially short and light rollers 11 are mounted on a shaft pin 13 which is attached to the piston rod end of the cylinder 17. Also connected to the shaft 13 is a pivot arm 12 limiting the vertical movement of the shaft 13. The pivot arm 12 is attached by a hinge pin 14 to a lug on the side of the housing 7. The stop stops 15, 16 determine the limits of the pivoting movement of the arm 12. The lower position limiter stop 15 must be adjustable during bending. The stop stop 15 can be, for example, a flat spring, which is curved by a power device as the glass bends in the direction of travel about a longitudinal axis. The stop stop 15 is not needed at all if the rollers 4 are flexible so as to bend into a continuous arc (Fig. 7) and the rollers 11 are allowed in their down position to respond to the rollers 4 (when the glass plate is not in between). If a lower stop stop 15 is used, the lower surface of the roller 11 in its lower position (if there is no glass between the rollers and rollers) is typically a few millimeters below the upper surface of the glass, but detached from the rollers 4. The upper position of the roller 11 may be fixed, e.g. from the level of the upper surface.

By adjusting the air pressure of the compressed air cylinder 17, the desired compressive force is achieved to promote the bending of the glass. If desired, the press force can also be adjusted zone by zone during bending. In this case, the cylinders 17 in different zones receive different pressures. The diameter of the pneumatic cylinder 17 is e.g. 8-10 mm and the length is preferably about 5 times the diameter to achieve a suitable elasticity. By common control of all the compressed air cylinders 17, all the rollers 11 can be moved simultaneously between said upper and lower extreme positions.

As shown in Fig. 2A, when the glass enters the bending and tempering compartment, the press wheels 11 are slightly detached from the surface of the glass in their upper position, or they can also lightly touch it. When the • glass is completely in the bending compartment (Fig. 2B), bending starts. At the same time, the desired and. an adjustable downward force that forces the glass to follow the rollers 4 of the earth-bending conveyor. However, the glass moves back and forth during oscillation bending. In the case shown 96110 6, the press rollers 11 and the conveyor rollers 4 overlap and in the lower position of the rollers 11 their distance is slightly smaller than the thickness of the glass sheet to be bent. When the leading edge of the glass sheet in the direction of movement comes between the roll 4 and the rollers 11, the rollers 11 move a small distance upwards against the force of the air spring 17.

Figure 3 shows a situation in which the glass has reached a certain degree of bending. At the same time as the conveyor is curved to the position shown in Fig. 3, the central area of the individual rollers is deflected downwards by the power device 18 as shown in Figs. 6 and 7. In the case of Fig. 6, the roll 4 is divided into two parts 4a and 4b, between which there is a pivot joint, the height of which can be changed by the power device 18. Alternatively, the roll parts 4a and 4b may be permanently deflected to a certain position, whereby the deflection is not changed during bending. When changing the degree of bending, the deflection is changed, for example, with a manual adjusting screw, which replaces the power unit 18. However, the deflection during bending may be more advantageous. The end bearings 19 should allow a slight rotation of the ends of the rollers.

Naturally, the shaft 4 can be divided into arbitrarily several parts.

It is also possible to use an arc-bending shaft 4 '(Fig. 7). In order to make the shaft 4 'thinner and more sensitive to bending, a flexible shaft can be used on which support rollers are arranged at short intervals. In this case, the shaft and the rollers together form a roll 4 ', above which the press rollers 11 are suspended on the compressed air cylinders 17.

When the final degree of bending is reached, a tempering blow is started while the glass sheet is still oscillating between the rollers 4 and the rollers 11. At the end of the hardening step, the upper pressure wheels 11 are raised and returned to their upper position. Rollers 11 il »iT» Hi. lii »'7 96110 The lower position is therefore the working position and the upper position is the rest position.

Figure 4 shows the arrangement of the press wheels, which are chosen so that they do not form successive rows with respect to the direction of travel of the glass. The press wheels are light in construction, they are well mounted for free rotation. The wheels have, for example, plastic frames and have a fibrous coating on the rim made of a material that can withstand high temperatures for a short time (approx. 630 ° C). The coating material can be any material used in roll coatings.

The flexible support method of the rollers and the adjustable clamping force are a substantial advantage over conventional benders in which the roller shafts are fixedly connected to the hardening housings.

Because the bending about the longitudinal axis is less, it is not necessary to bend the hardening housings in that direction. However, the hardening housings 5, 7 can also be divided in their longitudinal direction into two or more parts which can be deflected relative to each other in a manner corresponding to the deflection between the parts of the rollers 4 (e.g. 4a, 4b).

The invention is not limited to the above embodiment, but its structural details may vary in many ways. For example, other types of springs may be used instead of the air spring 17. The restriction of the movement of the rollers 11 to the upper and lower positions can also be implemented in many different ways. It is not necessary to hang the pressure rollers or wheels on the mouthpiece housings 7, but the suspension can take place on any structure. Two press wheels 11 can also be mounted on the same horizontal shaft 13 on one air spring 17.

*

Claims (11)

8 96110 A method for bending and tempering glass sheets, wherein the glass sheet is heated in a furnace (1) to a bending temperature, the heated glass sheet is transferred from a furnace to a bending and tempering section roll conveyor (3), surfaces when the glass sheet is on a curved roll conveyor, characterized in that the central area of the rollers (4) is deflected downwards from the plane of the roll ends and at the same time the pressure rollers (11) contacting the top surface of the glass sheet are pressed down with the desired pressing force. A method according to claim 1, characterized in that each press roller (11) is pressed by a separate air spring (17), which at the same time acts to move the press rollers (11) between an upper rest position and a lower working position. Method according to Claim 2, characterized in that different pressures are applied to the air springs (17) in different zones, the press rollers (11) in the different zones causing different pressing forces. • * Method according to one of Claims 1 to 3, characterized in that the press rollers (11) are moved from the rest position to the working position when the glass sheet to be bent has come from the oven to the conveyor (3) under the rollers (11). Ί 5. Apparatus for bending and tempering glass sheets, comprising a roller conveyor (3), the relative height of the rollers (4) of which can be adjusted to bend the conveyor to a curve corresponding to the desired degree of bending, lower tempering housings (5) with tempering holes (6) 96110 9 upper surfaces (9), and upper tempering housings (7) having * lower surfaces (10) with tempering openings (8), the tempering housings (5, 7) being movable to cause said upper and lower surfaces (9, 10) to follow the conveyor (3). ) curvature, characterized in that above the rollers (4) there is a plurality of press rollers (11) which can move vertically against the spring force to apply a pressing force to the upper surface of the glass, and that the central area of the rollers is deflected or deflected downwards. Device according to claim 5, characterized in that said spring force is provided by an air spring (17). Device according to claim 6, characterized in that said air spring (17) is a compressed air cylinder (17) which at the same time acts to move the pressure roller (11) between the rest position and the working position. Device according to any one of claims 5 to 7, characterized in that in the working position the distance of the lowest point of the presser roller (11) from the transport plane determined by the uppermost point of the conveyor rollers (4) is less than the thickness of the glass to be bent, the front edge of the glass increasing the force of said spring (17) against. Device according to one of Claims 5 to 8, characterized in that the rollers (4) are made of two or more axial successive parts (4a, 4b) between which there is a pivot joint, the height position of which can be varied by means of a power device (18). Device according to one of Claims 5 to 8, characterized in that the rollers (41) consist of flexible shafts which can be bent by a power device (18). 10 96110 Device according to one of Claims 5 to 10, characterized by stop stops (15 to 16) for determining the working position and the upper rest position of the pressure rollers (11). il 96110